[0001] The present invention relates to coated cemented carbide metalcutting inserts, especially
those of the indexable type.
[0002] The primary benefit of various coating materials to the metalcutting performance
of coated indexable cobalt cemented tungsten carbide inserts has been well documented.
Abrasion resistance (the most important consideration at lower cutting speeds) is
provided by titanium carbide (or titanium carbonitride). Resistance to tool-workpiece
chemical interaction (crater formation) is provided most commonly by alumina due to
this material having a very low free energy of formation. Titanium nitride is reputed
to lower tool-workpiece frictional forces and the occurrence of edge build-up. In
addition, its lustrous gold color enhances the marketability of the coated tool and
allows tool wear to be more readily observed.
[0003] The combined benefits of these materials have been used to advantage in first generation
multilayer coated tool inserts. Examples include the coating systems titanium carbide/titanium
carbonitride/titanium nitride and titanium carbide/alumina/titanium nitride. Additional
benefits are expected for second generation multilayer coatings designed to achieve
improved performance through optimization of layer thickness, number of layers and
the sequence of layer deposition.
[0004] The advantages of reduced grain size in chemical vapor deposition (CVD) coatings
applied to indexable cobalt cemented tungsten carbide inserts are well known. The
most commonly utilized method of reducing grain size in alumina layers is to periodically
interrupt the deposition of the alumina layer by depositing a thin layer of titanium
carbide, titanium carbonitride or titanium nitride between the alumina layers. In
this way, each succeeding alumina layer renucleates and grain growth is minimized.
The advantages of this procedure were demonstrated by Dreyer and Kolaska ("Development
and Tool Life Behavior of Super-Wear-Resistant Multilayer Coatings on Hardmetals,"
Metals Society (Book 278), London, England (1982), pages 112-117).
[0005] Considerable improvements in flank wear resistance have been observed when cutting
hot-worked steel (54 HRC), chilled cast iron and Inconel 718 with commercially available
multilayered alumina coated indexable inserts. These inserts utilized a ten layer
coating consisting of titanium carbide, titanium carbonitride, titanium nitride and
four layers of alumina separated by three layers of titanium nitride (Schintelmeister
et al, "Cutting Tool Materials Coated by Chemical Vapor Deposition," Wear, 100 (1984),
pages 153-169).
[0006] Improvements in both flank and crater wear performance have been demonstrated for
a multilayer alumina coated insert with an initial 3 micrometer µm thick layer of
titanium carbide overlaid by 19 layers of titanium nitride and 19 layers of alumina
to a total thickness of 6 µm. When machine tested against conventional 6 µm thick
titanium carbide coated and 5 µm/1 µm thick titanium carbide/alumina coated inserts,
the alumina multilayered insert demonstrated superior crater and flank wear resistance
in the machining of C60 steel. Superior performance of this alumina multilayered coating
was also observed during interrupted cutting of CK 45 KN steel (Dreyer et al, United
Kingdom Patent Application No. GB 2048960A).
[0007] EP-A-0 162 656 discloses a multilayer coated cemented carbide making use of the high
wear resistance of Al₂O₃ without lowering the toughness thereof. The cutting insert
described therein comprises a cemented carbide substrate, a backing layer consisting
of carbides, nitrides, carbo nitrides, carboxy nitrides, oxy nitrides, boro nitrides
or boro carbo nitrides of Ti, an active layer having a total thickness of 5 - 20 µm
consisting of alumina sublayers in which titanium oxide is dissolved or at most 30
v/o of titanium oxide is coexistent, each of said oxide sublayers having a thickness
of 0.01 to 2 µm and being divided by interlayers each having a thickness of 0.01 to
2 µm and consisting of TiC, TiN, TiCN, TiCNO, TiCO, TiNO, Ti-oxides, Ti(B, N), Ti(B,
N, C), SiC, AlN or AlON. In the examples a cemented carbide substrate is described
being composed of 85 w/o of WC, 10 w/o of (Ti, Ta, W)C and 5 w/o of Co. The titanium
oxide addition is said to increase the toughness of the cutting insert.
[0008] Applicants have now surprisingly discovered a multilayered coated cemented carbide
cutting insert possessing an excellent combination of edge strength, deformation resistance,
crater resistance and flank wear resistance, which make it commercially competitive
in a wide range of metalcutting applications such as continuous and interrupted machining
of carbon and alloy steels and gray and ductile cast irons.
[0009] A cutting insert is provided having a body with a rake face and a flank face, at
whose junction is a cutting edge. Preferably, the cutting insert is of the indexable
type, having more than one cutting edge. This body is composed of a cemented carbide
substrate having a coating bonded thereto. In accordance with the present invention,
the cemented carbide substrate consists essentially of: (1) tungsten carbide grains;
(2) solid solution carbide grains containing tungsten and an element selected from
the group consisting of titanium, hafnium, zirconium, tantalum and niobium; and (3)
6.1 to 6.5 weight percent (w/o) cobalt.
[0010] The substrate is characterized by a hardness of 90.8 to 91.6 Rockwell A and a magnetic
coercive force of 9,550 to 12,740 A/m (120 to 160 oerstads).
[0011] Preferably, tungsten carbide forms at least 80 w/o of the substrate, and more preferably,
at least 85 w/o of said substrate. Cobalt preferably is present at about 6.2 to 6.4
w/o of said substrate. Preferably, titanium, niobium and tantalum are present at 1.7
to 2.3, 1.2 to 1.8 and 3.2 to 3.8 w/o of the substrate, respectively. Preferably,
the hardness of the substrate is 91.0 to 91.6 Rockwell A.
[0012] The coating in accordance with the present invention consists of three layers, a
backing layer bonded to the substrate, an active layer bonded to the backing layer
and a finish layer bonded to the active layer. The backing layer has a thickness of
at least 5.0 micrometers µm and contains one or more layers selected from the group
of carbonitrides of titanium, hafnium and zirconium, alone or in combination with
each other. Preferably, the backing layer is titanium carbonitride of either uniform
or varying stoichiometry.
[0013] The active layer contains alternating sublayers of alumina and a nitride layer selected
from the group of nitrides of titanium, zirconium and hafnium, alone or in combination.
There are at least two layers of alumina separated by the nitride layer. The active
layer may start with either an alumina or nitride layer bonded directly to the backing
layer. Preferably, each alumina layer has a nominal thickness of less than about 1.5
µm and, more preferably, 0.5 to 1.0 µm, to assure that the average alumina grain size
is between about 0.15 to 0.5 µm and, therefore, of high hardness and excellent crater
resistance. Each alumina sublayer is separated from and bonded to the next alumina
sublayer by a nitride sublayer, preferably titanium nitride, having a preferred thickness
of about 1.0 µm or less and, more preferably, of about 0.2 to less than 1.0 µm.
[0014] The finish layer is bonded to the outermost alumina sublayer in the active layer
and has one or more sublayers selected from the group of the carbonitrides and nitrides
of titanium, alone or in combination. Preferably, the finish layer is formed of titanium
nitride having a total thickness of 0.2 to 4 µm.
[0015] In an alternative preferred embodiment, the finish layer is composed of two sublayers,
an inner sublayer of titanium carbonitride bonded to the last alumina sublayer, and
then an outermost layer of titanium nitride. In this last embodiment, the titanium
carbonitride sublayer has a preferred thickness of about 0.2 to 1.0 µm and the titanium
nitride sublayer has a preferred thickness of about 0.3 to 3.0 µm, and more preferably,
0.3 to 2.0 µm.
[0016] These and other aspects of the present invention will become more apparent upon review
of the following detailed description of the invention in conjunction with the drawings
which are briefly described below:
Figure 1 shows an isometric view of an embodiment of a cutting insert in accordance
with the present invention.
Figure 2 shows a typical microstructure of a substrate in accordance with the present
invention (at 1500x magnification).
Figure 3 shows a cross section through a preferred embodiment of the coating in accordance
with the present invention.
[0017] In accordance with the present invention, a multilayered cemented carbide metalcutting
insert 10 is provided as shown in Figure 1. The cutting insert 10 is preferably of
the indexable and invertable type having a body in which a rake face 12 and a flank
face 14 join to form a cutting edge 16.
[0018] As shown in Figures 2 and 3, the body is composed of a cemented carbide substrate
32 having a coating 34 bonded thereto. As shown in the photomicrograph (Figure 2)
the cemented carbide substrate consists essentially of tungsten carbide grains (light
gray phase), solid solution carbide grains (darker gray phase) containing tungsten
and one or more elements selected from the group of titanium, hafnium, zirconium,
tantalum and niobium, and 6.1 to 6.5 w/o cobalt (white phase). The substrate is characterized
by a hardness of 90.8 to 91.6 Rockwell A and a magnetic coercive force of 9,550 to
12,740 A/m (120 to 160 oerstads).
[0019] Preferably, the cobalt content of the cemented carbide substrate is 6.2 to about
6.4 w/o. It is applicants' belief that, at this combination of cobalt content and
tungsten carbide grain size (or binder phase thickness, as measured by magnetic coercive
force) and hardness, preferably 91 to 91.6, the substrate possesses a unique combination
of deformation resistance and toughness (or edge strength) which in combination with
the coating according to the present invention significantly contribute to its unique
metalcutting abilities.
[0020] Preferably, titanium, tantalum and niobium are also present as solid solution carbides.
Titanium is added for grain size control and deformation resistance, while tantalum
and/or niobium are added for thermal shock resistance. In a more preferred composition
in accordance with the present invention, the substrate contains about 1.7 to 2.3
w/o titanium and 4.4 to 5.6 w/o total of tantalum and niobium, with 3.2 to 3.8 w/o
tantalum and 1.2 to 1.8 niobium being most preferred.
[0021] Preferably, the substrate has a magnetic saturation of greater than 88 percent (more
preferably, 88 to 98 percent) and, preferably, contains only A or, at worst, A and
B type porosity.
[0022] The tungsten carbide content of the substrate is, preferably, at least 80 w/o and,
more preferably, at least 85 w/o.
[0023] The coating in accordance with the present invention (see Figure 3) consists of three
main layers or sections, a backing layer 36 bonded to the substrate 32, an active
layer 38 bonded to the backing layer 36, and a finish layer 40 bonded to the active
layer 38.
[0024] The backing layer 36 is formed of one or more layers or sublayers selected from the
group of carbonitrides of titanium, hafnium, zirconium, alone or in combination with
each other. Preferably, the backing layer is composed of carbonitrides of titanium
only. It has been found to be most preferable that the backing layer be made of a
single layer of titanium carbonitride, and that the backing layer has a thickness
of about 5 to 8 µm, preferably 5.5 to 7.5 µm, and more preferably, about 5.5 to 7.0
µm. It has been found that resistance to flank wear is proportional to the thickness
of the backing layer. The titanium carbonitride backing layer may be of a single chemistry
or it may be graded, i.e., have a carbon to nitrogen ratio that varies through its
thickness, e.g., carbon decreasing in a direction away from the substrate.
[0025] The active layer 38 contains alternating sublayers of alumina 42 and a nitride 44
selected from the group of nitrides of titanium, zirconium and hafnium, alone or in
combination. The active layer may start with an alumina or nitride sublayer bonded
directly to the backing layer. In order to obtain high hardness alumina sublayers
having enhanced crater wear resistance, each alumina layer should have a fine grain
size, preferably with a median grain size in the range of about 0.15 to 0.5 µm. This
fine grain size is obtained by keeping the thickness of each alumina layer to less
than about 1.5 µm and, more preferably, about 0.5 to about 1.0 µm. In order to maximize
crater resistance, at least two, and preferably at least three or four, alumina sublayers
42 of the type described above are provided. Preferably, the total thickness of the
alumina sublayers in the active layer is about 2.3 to 4.0 µm. Each alumina sublayer
is separated from the next by a nitride sublayer, which is preferably titanium nitride.
This nitride sublayer not only separates the alumina sublayers, allowing the cumulative
thickness of fine grained, crater resistant alumina, to be increased, but it also
serves to adherently bond one alumina sublayer to the next. Tests performed by applicants
indicate that titanium nitride sublayers provide significantly better adherence to
the alumina sublayers than either titanium carbide or titanium carbonitride. The thickness
of each nitride sublayer 44 should be at least about 0.2 µm to assure complete coverage
of the underlying alumina sublayer, but no more than about 1.0 µm, since there is
no advantage to increased thickness. The active layer preferably has a total thickness
of 3 to 8 µm and, more preferably, 3 to 5.5 µm.
[0026] Bonded to the last alumina sublayer 42 in the active layer 38 is a finish layer 40.
The finish layer is designed to provide a low friction surface to the coating 34 and
to minimize metal build-up on the coating during metalcutting operations.
[0027] The finish layer 40 contains one or more layers or sublayers selected from the group
of the carbonitrides and nitrides of titanium, alone or in combination. Preferably,
the finish layer is formed of titanium nitride having a thickness of 0.2 to 4 µm.
In the alternative preferred embodiment shown in Figure 3, the finish layer 40 is
composed of two sublayers, an inner sublayer 46 of titanium carbonitride bonded to
the last alumina sublayer 42, and then an outermost sublayer 48 of titanium nitride
bonded to the titanium carbonitride sublayer 46. In this last embodiment, the titanium
carbonitride sublayer has a preferred thickness of about 0.2 to 1.0 µm and the titanium
nitride sublayer has a preferred thickness of about 0.3 to 3.0 µm and, more preferably,
0.3 to 2.0 µm.
[0028] As coating thickness increases, residual stresses build up in the coatings, which
can reduce the strength or integrity of the coatings and lead to reductions in metalcutting
performance. Therefore, the coating 34 total thickness is in the range of 7.5 to 20
µm, with about 8 to 15 µm being preferred and about 9 to 12.5 µm being more preferred.
[0029] The coating described above may be applied by conventional chemical vapor deposition
processes well known to those of ordinary skill in the art in the metalcutting insert
field. The nitride coatings described above may also be applied by physical vapor
deposition (PVD) techniques, also well known to those of ordinary skill in the art.
For example, in the coatings described herein, it is contemplated that all coating
layers may be applied by automated CVD techniques. Alternatively, for example, the
titanium nitride layer in the finish layer may be applied by PVD techniques.
[0030] The present invention will become more clear upon review of the following examples
which are meant to be only illustrative of the present invention.
[0031] The charge materials shown in Table 1 were milled in a 18.1 cm x 38.1 cm (7.125 inch
x 15 inch) mill jar with 45,000 grams of cemented tungsten carbide cycloids and heptane
for 19 hours to produce a Fisher SubSieve Size (FSSS) (ASTM 330-82) apparent particle
size of 1.2 µm. The milled slurry was then poured through a 37 µm (400 mesh) sieve
into a sigma dryer. Liquid paraffin and ethomeen levels of 2 percent and 0.25 percent,
respectively, were then added and the slurry was then mixed and dried in the sigma
blender. The resulting mixture was then Fitzmilled through a 1.02 mm (0.040 inch)
screen.
[0032] Inserts were then pill pressed and sintered to full density at 1454°C (2650°F)for
30 minutes under about a 25 µm vacuum. The sintered product was then ground and honed
to a SNGN-433 (ANSI B 212.4-1986) style indexable insert substrate.
[0033] Examination of the sintered product (batch 1) showed that it had a magnetic saturation
of 98 percent, a magnetic coercive force of 11,940 A/m (150 oerstads) and a Rockwell
A hardness of 91.4 - 91.5. The tungsten carbide grain size ranged from 1 to 7 µm with
a few larger tungsten carbide grains up to 17 µm. The solid solution carbide grain
size ranged from 1 to 4 µm (see Figure 2). The porosity of the substrate was rated
as AO2 - B00.1 - C00. No cobalt enrichment or solid solution carbide depletion was
observed at or near the substrate surface.
[0034] Two additional batches (batches 2 and 3) of substrates were made having the same
nominal composition as that described above and processed in a manner similar to that
described above. These two batches were, however, pressure sintered by sintering for
30 minutes at 1454°C (2650°F) in vacuum followed by 30 minutes pressurization at temperature
and then further sintering at 1454°C (2650°F) for 30 minutes at 2.07 MPa (300 psi)
argon.
[0035] Batch 2 sintered product had a magnetic saturation of 96 percent of saturation, a
magnetic coercive force of 10,350 A/m (130 oerstads) and a Rockwell A hardness of
91.2. The tungsten carbide grain size ranged from about 1 to 7 µm. The solid solution
carbide grain size ranged from about 1 to 4 µm. The porosity of the substrate was
AO2 - B00-2 - C00. Cobalt enrichment and solid solution carbide depletion were observed
extending inwardly about 14 and 19.1 µm, respectively, in from the substrate surface.
[0036] Batch 3 sintered substrates had a magnetic saturation of 91 percent of saturation,
a magnetic coercive force of 11,000 A/m (138 oerstads) and a Rockwell A hardness of
91.4. The microstructure was similar to the Batch 1 microstructure (i.e., no cobalt
enrichment or solid solution carbide depletion observed at the substrate surface).
[0037] The substrates from batches 2 and 3 were cleaned and then coated in a production
size CVD reactor to provide one of the two nominal coating structures outlined below:
|
Coating 1 |
Coating 2 |
Backing Layer: |
5.5µm TiCN |
6.0µm TiCN |
0.5µm TiCN graded to TiN |
|
Active Layer: |
1.0µm Al₂O₃ |
1.0µm Al₂O₃ |
0.5µm TiN |
0.5µm TiN |
1.0µm Al₂O₃ |
1.0µm Al₂O₃ |
0.5µm TiN |
0.5µm TiN |
1.0µm Al₂O₃ |
1.0µm Al₂O₃ |
Finish Layer: |
0.3µm TiCN |
0.3µm TiCN |
0.7µm TiN |
0.7µm TiN |
Total Nominal Coating Thickness |
11.0µm |
11.0µm |
[0038] The coatings 1 and 2 were respectively applied by the methods 1 and 2 shown in Table
2.
[0039] The nominal coating thicknesses reported above were measured on the rake face, approximately
2.54 mm (0.1 inches) away from the cutting edge nose, to avoid edge effects. Actual
coating thicknesses measured (SNMG-433) on the type 2 coating on batches 2 and 3 as
shown below:
|
Batch 2/Coating 2(µm) |
Batch 3/Coating 2(µm) |
TiCN |
6.5 |
6.8 |
Al₂O₃ |
1.0 |
1.0 |
TiN |
0.3 |
0.3 |
Al₂O₃ |
0.8 |
0.8 |
TiN |
0.4 |
0.3 |
Al₂O₃ |
0.7 |
0.5 |
TiCN |
0.3 |
0.3 |
TiN |
0.6 |
0.9 |
[0040] Metalcutting tests using these inserts and inserts in other common geometry styles
made in essentially the manner described above have provided excellent cutting performance
in the turning of a variety of steels and good cutting performance in the turning
of both gray and ductile cast irons. Inserts in accordance with the present invention
have also exhibited excellent edge strength in interrupted cutting tests on steel
and cast iron.
[0041] Inserts made essentially in accordance with the above procedures were made in the
SNMG-433 geometry style (0.051 to 0.102 mm (.002 to .004 inch) radius hone) and subjected
to the slotted bar edge strength tests described below in Table 3. The slotted bar
utilized had four slots at 90° to each other running the length of the bar. The width
of each slot was 0.48 cm (3/16 inch).
TABLE 3
SLOTTED BAR EDGE STRENGTH TEST--AISI 41L50 STEEL |
|
Number of Impacts at 107 surface meters (350 Surface Ft.)/Min. |
|
Batch 2 Coating 1 |
Batch 3 Coating 1 |
Batch 2 Coating 2 |
Batch 3 Coating 2 |
Average* |
597+ |
310 |
409+ |
387 |
Standard Deviation |
226 |
274 |
351 |
212 |
|
Number of Impacts at 198 surface meters (650 Surface Ft.)/Min. |
|
Batch 2 Coating 1 |
Batch 3 Coating 1 |
Batch 2 Coating 2 |
Batch 3 Coating 2 |
Average* |
502 |
421 |
636 |
577 |
Standard Deviation |
152 |
159 |
77 |
147 |
Test Conditions
15° lead angle/cutting diameter
11.43 to 8.89 cm (4.50 inch to 3.50 inch) (for 107 m/min (350 sfm)) and 14.68 to 11.63
cm (5.78 inch to 4.58 inch) (for 198 m/min (650 sfm))/
Feed rates: 0.37, 0.51, 0.61, 0.74, 0.91, 1.02, 1.17, 1.35 mm (0.0145, 0.020, .024,
.029, .036, .040, .046, .053 inch)- 100 impacts at each feed until breakage/2.54 mm
(0.100 inch) depth of cut / no coolant |
*Each average is an average of 7 to 8 cutting edge tests. The plus sign indicates
that at least one edge underwent 800 impacts without failure, at which time the test
was stopped. |
[0042] In a manner similar to the above, additional cutting inserts were made having the
batch 1 substrate but with the following nominal coating structures:
|
Coating Structure |
|
3 |
4 |
5 |
Backing Layer |
2.5µm TiC |
5.0µm TiCN |
2.5µm TiC |
2.5µm TiCN |
|
2.5µm TiCN |
Active Layer |
1µm Al₂O₃ |
1µm Al₂O₃ |
1µm Al₂O₃ |
0.5µm TiN |
0.5µm TiN |
0.5µm TiN |
1.0µm Al₂O₃ |
0.5µm TiN |
1.0µm Al₂O₃ |
1.0µm Al₂O₃ |
1.0µm Al₂O₃ |
0.5µm TiN |
0.5µm TiN |
0.5µm TiN |
1.0µm Al₂O₃ |
1.0µm Al₂O₃ |
1.0µm Al₂O₃ |
|
Finish Layer |
0.5-1.0µm TiN |
0.5-1.0µm TiN |
0.5-1.0µm TiN |
[0043] The batch 1 cutting inserts having the coating styles 3-5 were then subjected to
the following tests (Tables 4-13):
TABLE 4
Tool Material |
Tool Life (min) & Failure Mode |
Avg. |
Coating 3 |
6.8 cr |
7.2 mw* |
5.5 cr |
6.5 |
Coating 4 |
7.0 mw |
6.8 mw |
7.2 cr |
7.0 |
Coating 5 |
7.0 mw |
5.0 ch* |
7.5 fw |
6.5 |
*NOTE: Flaking of the coating was noted. |
Turning AISI 1045 steel (200 BHN)
213 m/min (700 sfm) / 0.58 mm/rev. (.023 ipr) / 2.03 mm (.080") doc
CNMG-432 style (0.025 to 0.051 mm (.001 - .002 inch) radius hone)
-5° lead angle / no coolant
Tool Life Criteria:
- fw --
- 0.381 mm (.015") uniform flank wear
- mw --
- 0.762 mm (.030") maximum localized flank wear
- cr --
- 0.102 mm (.004") crater wear
- ch --
- 0.762 mm (.030) chip
- bk --
- breakage
TABLE 5
Tool Material |
Tool Life (min) & Failure Mode |
Avg. |
Coating 3 |
7.4 fw |
5.6 mw* |
6.6 mw* |
6.5 |
Coating 4 |
12.4 ms |
14.6 mw |
13.0 mw |
13.3 |
Coating 5 |
9.1 fw |
12.2 mw |
10.2 mw |
10.5 |
*NOTE: Flaking of the coating was noted. |
Turning 1045 steel (200 BHN)
259 m/min (850 sfm) / 0.38 mm/rev. (.015 ipr) / 2.03 mm (.080") doc
CNMG-432 style (0.025 to 0.051 mm (.001 - .002 inch) radius hone)
-5° lead angle / no coolant
Tool Life Criteria: same as Table 4
TABLE 6
Tool Material |
Tool Life (min) & Failure Mode |
Avg. |
Coating 4 |
19.6 cr |
17.7 cr* |
18.4 cr |
18.6 |
*NOTE: Flaking of the coating was noted. |
Turning 1045 steel (200 BHN)
259 m/min (850 sfm) / 0.38 mm/rev. (.015 ipr) / 2.03 mm (.080") doc
SNGN-433 style (0.025 to 0.076 mm (.001 - .003 inch) radius hone)
15° lead angle / no coolant
Tool Life Criteria: same as Table 4
TABLE 7
Tool Material |
Tool Life (min)& Failure Mode |
Avg. |
Coating 4 |
5.8 fw |
5.8 fw |
5.8 |
Turning ASTM A536 80-55-06 ductile iron (248 BHN)
183 m/min (600 sfm) / 0.51 mm/rev. (.020 ipr) / 2.54 mm (.100") doc
SNGN-433 style (0.025 to 0.076 mm (.001 - .003 inch) waterfall hone)
15° lead angle / no coolant
Tool Life Criteria: same as Table 4
TABLE 8
Tool Material |
Tool Life (min) & Failure Mode |
Avg. |
Coating 3 |
13.2 fw |
14.8 fw |
14.0 |
Coating 4 |
17.0 fw |
15.7 cr |
16.4 |
Coating 5 |
14.0 fw |
12.8 fw |
13.4 |
Turning ASTM 536 65-45-12 ductile iron (163 BHN)
259 m/min (850 sfm) / 0.51 mm/rev. (.020 ipr) / 2.54 mm (.100") doc
SNGN-433 style (0.025 to 0.076 mm (.001 - .003 inch) waterfall hone)
15° lead angle / no coolant
Tool Life Criteria: same as Table 4
TABLE 9
Tool Material |
Tool Life (min) & Failure Mode |
Avg. |
Coating 4 |
17.5 cr |
3.0 ch |
13.3 cr |
11.3 |
Turning ASTM A536 65-45-12 ductile iron (163 BHN)
259 m/min (850 sfm) / 0.51 mm/rev. (.020 ipr) / 2.54 mm (.100") doc
SNGN-433 style (0.025 to 0.076 mm (.001 - .003 inch) waterfall hone)
15° lead angle / no coolant
Tool Life Criteria: same as Table 4
TABLE 10
Tool Material |
Tool Life (min) & Failure Mode |
Coating 4 |
20.6 cr |
Turning ASTM A536 65-45-12 ductile iron (163 BHN)
213 m/min (700 sfm) / 0.762 mm/rev. (.030 ipr) / 2.54 mm (.100") doc
SNGN-433 style (0.025 to 0.076 mm (.001 - .003 inch) waterfall hone)
15° lead angle / no coolant
Tool Life Criteria: same as Table 4
TABLE 11
Tool Material |
Tool Life (min) & Failure Mode |
Avg. |
Coating 4 |
4.3 fw |
4.6 fw |
4.5 |
Flycut Milling ASTM A536 60-40-18 ductile iron (182 BHN)
213 m/min (700 sfm) / 0.38 mm/rev. (.015 ipt) / 2.54 mm (.100") doc SNGN-433 style
(0.025 to 0.076 mm (.001 - .003 inch) waterfall hone) / no coolant
15° lead angle / 20.3 cm (8 inch) flycutter cutter diameter / 10.2 cm (4 inch) width
/ 61 cm (24 inch) length / straddle type
Tool Life Criteria:
- fw --
- 0.381 mm (.015") uniform flank wear
- cr --
- 0.102 mm (.004") crater depth
- ch --
- 0.762 mm (.030") chip
- bk --
- breakage
TABLE 12
Tool Material |
Tool Life (min) & Failure Mode |
Avg. |
Coating 4 |
8.6 cr |
7.8 fw |
8.2 |
Flycut Milling ASTM A536 60-40-18 ductile iron (182 BHN)
213 m/min (700 sfm) / 0.18 mm/rev. (.007 ipt) / 2.54 mm (.100") doc SNGN-433 style
(0.025 to 0.076 mm (.001 - .003 inch) waterfall hone) / no coolant
15° lead angle / 20.3 cm (8 inch) flycutter cutter diameter / 10.2 cm (4 inch) width
/ 61 cm (24 inch) length / straddle type
Tool Life Criteria:
- fw --
- 0.381 mm (.015") uniform flank wear
- cr --
- 0.102 mm (.004") crater depth
- ch --
- 0.762 mm (.030") chip
- bk --
- breakage
TABLE 13
Tool Material |
Tool Life (min) & Failure Mode |
Avg. |
Coating 4 |
4.4 cr |
5.0 ch |
4.7 |
Flycut Milling ASTM A536 60-40-18 ductile iron (182 BHN)
366 m/min (1200 sfm) / 0.18 mm/rev. (.007 ipt) / 2.54 mm (.100") doc SNGN-433 style
(0.025 to 0.076 mm (.001 - .003 inch) waterfall hone)
15° lead angle / 20.3 cm (8 inch) flycutter cutter diameter / 10.2 cm (4 inch) width
/ 61 cm (24 inch) length / straddle type
Tool Life Criteria:
- fw --
- 0.381 mm (.015") uniform flank wear
- cr --
- 0.102 mm (.004") crater depth
- ch --
- 0.762 mm (.030") chip
- bk --
- breakage
It is submitted that the foregoing test results indicate that the cutting inserts
according to the present invention possess an excellent combination of flank wear
resistance, crater wear resistance and edge strength in the machining of steels providing
long tool lives in both continuous and interrupted machining operations. Good tool
lives were exhibited in the machining of ductile cast irons.
1. A cutting insert comprising a body having a rake face and a flank face; and a cutting
edge at a junction of said rake face and said flank face; with said body being composed
of:
a cemented carbide substrate consisting essentially of tungsten carbide grains,
solid solution carbide grains containing tungsten and an element selected from the
group consisting of titanium, tantalum, niobium, zirconium and hafnium, alone or together,
and 6.1 to 6.5 weight percent cobalt, said substrate having a hardness of 90.8 to
91.6 Rockwell A and a magnetic coercive force of 9,550 to 12,740 A/m (120 to 160 oerstads);
a coating bonded to said substrate;said coating including a backing layer bonded
to said substrate, having a thickness of at least 5 micrometers, and selected from
the group consisting of the carbonitrides of titanium, hafnium and zirconium, alone
or in combination; an active layer composed of alternating sublayers including at
least a plurality of alumina sublayers, each having a fine grain size and a nominal
thickness of less than 1.5 µm, and separated from each other by an intermediate sublayer
selected from the group consisting of the nitrides of titanium, zirconium and hafnium,
alone or in combination, and said active layer starting with either an alumina or
intermediate sublayer bonded to said backing layer; and
a finish layer bonded to the outermost alumina layer; said finish layer selected
from the group consisting of the carbonitrides and nitrides of titanium, alone or
in combination.
2. The cutting insert according to claim 1 wherein the hardness of said substrate is
91.0 to 91.6 Rockwell A.
3. The cutting insert according to any one of claims 1 or 2 wherein cobalt forms 6.2
to 6.4 w/o of said substrate.
4. The cutting insert according to any one of claims 1 to 3 wherein said backing layer
consists of titanium carbonitride.
5. The cutting insert according to any one of claims 1 to 4 wherein said intermediate
sublayers consist of titanium nitride.
6. The cutting insert according to any one of claims 1 to 3 further characterized in
that said backing layer includes a layer of titanium carbonitride and said backing
layer has a thickness of 5 to 8 µm;
7. The cutting insert according to any one of claims 1 to 6 wherein said finish layer
includes a titanium carbonitride finish layer bonded to one of said alumina layers,
and a titanium nitride finish layer bonded to said titanium carbonitride finish layer.
8. The cutting insert according to any one of claims 1 to 7 wherein each of said intermediate
sublayers is titanium nitride having a nominal thickness of about 0.2 to 1.0 µm.
9. The cutting insert according to any one of claims 1 to 8 further characterized in
that the total thickness of the alumina sublayers in the active layer is about 2.3
to 4.0 µm.
10. The cutting insert according to any one of claims 1 to 9 characterized in that said
finish layer has a thickness of about 0.2 to 4 µm of titanium nitride.
11. The cutting insert according to any one of the foregoing claims, characterized in
that the carbon content of said backing layer varies, with the carbon content decreasing
in a direction away from said substrate.
1. Schneideinsatz mit einem Körper, der eine Spanfläche und eine Freifläche aufweist,
und mit einer Schneidkante am Zusammentreffen der Spanfläche und der Freifläche, wobei
der Körper zusammengesetzt ist aus:
einem Hartmetallsubstrat, das im wesentlichen aus Wolframkarbidkörnern, in fester
Lösung vorliegenden, Wolfram und ein aus der aus Titan, Tantal, Niob, Zirkonium und
Hafnium, allein oder zusammen, bestehenden Gruppe ausgewähltes Element enthaltenden
Karbidkörnern und 6,1 bis 6,5 Gew.% Kobalt besteht, wobei das Substrat eine Härte
von 90,8 bis 91,6 Rockwell A und eine magnetische Koerzitivkraft von 9.550 bis 12.740
A/m (120 bis 160 Oersted) aufweist, und
einer an das Substrat gebundenen Beschichtung, wobei die Beschichtung eine Grundschicht
umfaßt, die an das Substrat gebunden ist, eine Dicke von wenigstens 5 µm aufweist
und aus der aus den Karbonitriden von Titan, Hafnium und Zirkonium, allein oder in
Kombination miteinander, bestehenden Gruppe ausgewählt ist, wobei die Beschichtung
ferner eine aktive Schicht umfaßt, die aus alternierenden, mindestens eine Mehrzahl
von Aluminiumoxidteilschichten einschließenden Teilschichten aufgebaut ist, wobei
jede der Aluminiumoxidteilschichten eine feine Korngröße und eine nominale Dicke von
weniger als 1,5 µm hat, und wobei die Aluminiumoxidteilschichten voneinander durch
eine aus der aus den Nitriden von Titan, Zirkonium und Hafnium, allein oder in Kombination
miteinander, bestehenden Gruppe ausgewählte dazwischenliegende Teilschicht getrennt
sind, und wobei die aktive Schicht entweder mit einer Aluminiumoxidteilschicht oder
einer dazwischenliegenden Teilschicht beginnt, die an die Grundschicht gebunden sind,
und wobei die Beschichtung eine an die äußerste Aluminiumoxidschicht gebundene Endschicht
umfaßt, die aus der aus den Karbonitriden und Nitriden von Titan, allein oder in Kombination
miteinander, bestehenden Gruppe ausgewählt ist.
2. Schneideinsatz nach Anspruch 1, dadurch gekennzeichnet, daß die Härte des Substrats
91,0 bis 91,6 Rockwell A beträgt.
3. Schneideinsatz nach einem der Ansprüche 1 oder 2, dadurch gekennzeichnet, daS das
Kobalt 6,2 bis 6,4 Gew.% des Substrats bildet.
4. Schneideinsatz nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Grundschicht
aus Titankarbonitrid besteht.
5. Schneideinsatz nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die dazwischenliegenden
Teilschichten aus Titannitrid bestehen.
6. Schneideinsatz nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Grundschicht
eine Titankarbonitridschicht umfaßt und eine Dicke von 5 bis 8 µm hat.
7. Schneideinsatz nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß die Endschicht
eine an eine der Aluminiumoxidschichten gebundene Titankarbonitridendschicht und eine
an die Titankarbonitridendschicht gebundene Titannitridendschicht umfaßt.
8. Schneideinsatz nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, daß jede
der dazwischenliegenden Teilschichten aus Titannitrid besteht und eine nominale Dicke
von etwa 0,2 bis 1,0 µm aufweist.
9. Schneideinsatz nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, daß die Gesamtdicke
der Aluminiumoxidteilschichten in der aktiven Schicht etwa 2,3 bis 4,0 µm beträgt.
10. Schneideinsatz nach einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, daß die Endschicht
eine Dicke von etwa 0,2 bis 4 µm aus Titannitrid aufweist.
11. Schneideinsatz nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß
der Kohlenstoffgehalt der Grundschicht variiert und in einer von dem Substrat wegführenden
Richtung abnimmt.
1. Pièce rapportée de coupe comprenant un corps ayant une face de coupe et une face de
dépouille ; et une arête de coupe à la jonction de ladite face de coupe et de ladite
face de dépouille ; ledit corps étant constitué de :
un substrat en carbure cémenté constitué essentiellement de grains de carbure de
tungstène, de grains de carbure en solution solide contenant du tungstène et un élément
choisi dans le groupe formé par le titane, le tantale, le niobium, le zirconium et
le hafnium, seuls ou en association, et de 6,1 à 6,5 pour cent en poids de cobalt,
ledit substrat ayant une dureté Rockwell A de 90,8 à 91,6 et une force coercitive
magnétique de 9550 à 12 740 A/m (120 à 160 oersteds) ;
un revêtement lié audit substrat ; ledit revêtement comprenant une couche de base
liée au substrat, ayant une épaisseur d'au moins 5 micromètres, et choisie dans le
groupe formé par les carbonitrures de titane, de hafnium et de zirconium, seuls ou
en association ; une couche active constituée de sous-couches alternées comprenant
au moins plusieurs sous-couches d'alumine ayant chacune une fine taille de grains
et une épaisseur nominale inférieure à 1,5 µm et séparées les unes des autres par
une sous-couche intermédiaire choisie dans le groupe formé par les nitrures de titane,
de zirconium et de hafnium, seuls ou en association, et ladite couche active commençant
soit par une sous-couche d'alumine, soit par une sous-couche intermédiaire, liée à
ladite couche de base ; et
une couche de finition liée à la couche d'alumine extérieure ; ladite couche de
finition étant choisie dans le groupe formé par les carbonitrures et nitrures de titane,
seuls ou en association.
2. Pièce rapportée de coupe selon la revendication 1, dans laquelle la dureté Rockwell
A dudit substrat est de 91,0 à 91,6.
3. Pièce rapportée de coupe selon l'une quelconque des revendications 1 et 2, dans laquelle
le cobalt constitue 6,2 à 6,4 % en poids dudit substrat.
4. Pièce rapportée de coupe selon l'une quelconque des revendications 1 à 3, dans laquelle
ladite couche de base consiste en carbonitrure de titane.
5. Pièce rapportée de coupe selon l'une quelconque des revendications 1 à 4, dans laquelle
lesdites sous-couches intermédiaires consistent en nitrure de titane.
6. Pièce rapportée de coupe selon l'une quelconque des revendications 1 à 3, caractérisée
de plus par le fait que ladite couche de base comprend une couche de carbonitrure
de titane et ladite couche de base a une épaisseur de 5 à 8 µm.
7. Pièce rapportée de coupe selon l'une quelconque des revendications 1 à 6, dans laquelle
ladite couche de finition comprend une couche de finition en carbonitrure de titane
liée à l'une desdites couches d'alumine, et une couche de finition en nitrure de titane
liée à ladite couche de finition en carbonitrure de titane.
8. Pièce rapportée de coupe selon l'une quelconque des revendications 1 à 7, dans laquelle
chacune desdites sous-couches intermédiaires est du nitrure de titane ayant une épaisseur
nominale d'environ 0,2 à 1,0 µm.
9. Pièce rapportée de coupe selon l'une quelconque des revendications 1 à 8, caractérisée
de plus par le fait que l'épaisseur totale des sous-couches d'alumine dans la couche
active est d'environ 2,3 à 4,0 µm.
10. Pièce rapportée de coupe selon l'une quelconque des revendications 1 à 9, caractérisée
par le fait que ladite couche de finition a une épaisseur d'environ 0,2 à 4 µm de
nitrure de titane.
11. Pièce rapportée de coupe selon l'une quelconque des revendications précédentes, caractérisée
par le fait que la teneur en carbone de ladite couche de base varie, la teneur en
carbone diminuant dans le sens qui s'éloigne dudit substrat.